The munged daemon is responsible for authenticating local MUNGE clients
and servicing their credential encode & decode requests. All munged
daemons within a security realm share a secret key. This key is used to
protect the contents of a credential.
When a credential is created, munged embeds metadata within it
including the effective UID and GID of the requesting client (as determined
by munged) and the current time (as determined by the local clock).
It then compresses the data, computes a message authentication code, encrypts
the data, and base64-encodes the result before returning the credential to
When a credential is validated, munged first checks the message
authentication code to ensure the credential has not been subsequently altered.
Next, it checks the embedded UID/GID restrictions to determine whether the
requesting client is allowed to decode it. Then, it checks the embedded
encode time against the current time; if this difference exceeds the embedded
time-to-live, the credential has expired. Finally, it checks whether this
credential has been previously decoded on this host; if so, the credential
has been replayed. If all checks pass, the credential metadata and payload
are returned to the client.
Display a summary of the command-line options.
Display license information.
Display version information.
Force the daemon to run if at all possible. This overrides warnings for an
existing local domain socket, a lack of entropy for the PRNG, and insecure
Run the daemon in the foreground.
-S, --socket path
Specify the local domain socket for communicating with clients.
Specify an alternate directory in which the daemon will create the pipe used to
authenticate clients. The recommended permissions for this directory are 0711.
This option is only valid on platforms where client authentication is performed
via a file-descriptor passing mechanism.
Specify an alternate directory in which clients will create the file used to
authenticate themselves to the daemon. The recommended permissions for this
directory are 1733. This option is only valid on platforms where client
authentication is performed via a file-descriptor passing mechanism.
Specify whether the modification time of /etc/group should be checked
before updating the supplementary group membership mapping. If this value is
non-zero, the check will be enabled and the mapping will not be updated unless
the file has been modified since the last update.
Specify the number of seconds between updates to the supplementary group
membership mapping; this mapping is used when restricting credentials by GID.
A value of 0 causes it to be computed initially but never updated (unless
triggered by a SIGHUP). A value of -1 causes it to be disabled.
Specify an alternate secret key file.
Specify the number of threads to spawn for processing credential requests.
Immediately update the supplementary group membership mapping instead of
waiting for the next scheduled update; this mapping is used when restricting
credentials by GID.
Terminate the daemon.
All clocks within a security realm must be kept in sync within the credential
While munged prevents a given credential from being decoded on a
particular host more than once, nothing prevents a credential from being
decoded on multiple hosts within the security realm before it expires.
Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
Copyright (C) 2002-2007 The Regents of the University of California.
MUNGE is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version. Additionally for the MUNGE library (libmunge), you
can redistribute it and/or modify it under the terms of the GNU Lesser
General Public License as published by the Free Software Foundation,
either version 3 of the License, or (at your option) any later version.